Climate Change And The Astrobiology Of The Anthropocene

The author of this article is an astrophysics professor who is self-described ‘evangelist of science’. He is deeply committed to Scientism, or the belief that science is the sole source of truth in the universe. ⁃ TN Editor

You can’t solve a problem until you understand it. When it comes to climate change, on a fundamental level we don’t really understand the problem.

For some time now, I’ve been writing about the need to broaden our thinking aboutclimate. That includes our role in changing it — and the profound challenges those changes pose to our rightly cherished “project” of civilization.

Today, I want to sharpen the point.

But first, as always, let’s be clear: We have not gotten the science wrong. The Earth’s climate is changing because of human activity. That part has been well-established for awhile now, in spite of the never ending — and always depressing — faux “climate debate” we get in politics.

But the part of climate change we’ve failed to culturally metabolize is the meaning of what’s happening to us and the planet.

In other words, what we don’t get is the true planetary context of the planetary transformation human civilization is driving. Getting this context right is, I think, essential — and I’m dedicating most of the year to writing a book on the subject. The book’s focus is what I believe should be a new scientific (and philosophical) enterprise: the astrobiology of the Anthropocene.

I meet a lot of folks who’ve heard of both astrobiology and the Anthropocene before. In general, however, lots of people look at me a bit sideways when I use either word, much less lump them together as the future of humanity.

Given that experience, let’s start with a couple of definitions.

A trip to NASA’s astrobiology homepage will tell you the field is all about understanding life in its planetary context. It might seem strange to have an entire scientific domain dedicated to a subject for which we have just one example (i.e. life on Earth). But take that perspective and you’d miss the spectacular transformation astrobiology has brought to our understanding of life and its possibilities in the universe.

All those planets we’ve discovered orbiting other stars are part of astrobiological studies. The robot rovers rolling around Mars proving that the planet was once warm and wet — they are astrobiology, too. The same is true for work on Earth’s deep history. These studies show us that Earth has been many planets in its past: a potential water world before major continents grew; a totally glaciated snowball world; a hothouse jungle planet. In understanding these transformations, we’ve gotten to see one example of life and a planet co-evolving over billions of years.

If you want an example, consider how cyanobacteria, or blue-green algae, completely reworked the planet’s atmosphere 2.5 billion years ago giving us the oxygen-rich air we breathe today. Another example is the work showing how after the retreat of Ice Age glaciers, Earth entered a warm, wet and climatically stable period that geologists call the Holocene — about 10,000 years ago.

The Geologic History of Earth. Note the timescales. We are currently in the Holocene, which has been warm and moist and a great time to grow human civilization. But the activity of civilization is now pushing the planet into a new epoch which scientists call the Anthropocene.Ray Troll/Troll Art

The Holocene has been a good time for human civilization to emerge and thrive. The seasons have been pretty regular, moving between relatively mild boundaries of hot-ish and cold-ish. That transition was the key change and allowed humans to get stable and productive agriculture started.

But, thanks to civilization, the Holocene is now at an end. That’s where the story gets really interesting and where the Anthropocene makes its entrance.

Scientists now recognize that our impact on Earth has become so significant we’ve pushed it out of the Holocene into the Anthropocene, an entirely new geological epoch dominated by our own activity (see Andy Revkin’s reporting on the subject). And it’s not just about climate change. Human beings have now “colonized” more than 50 percent of the planet’s surface. And we drive flows of key planetary substances, like potassium, far above the “natural” levels.

It may seem impossible to some folks that a bunch of hairless “primates” could change an entire planet. But that view misses the most important part of our story, the part that speaks directly to our moment in planetary evolution.

What I’m interested in, now, is putting these two ideas together: the astrobiology of the Anthropocene. That means looking at what’s happening to us today from the broadest possible perspective. A couple of years ago, my colleague Woody Sullivan and I published a paper titled “Sustainability and the Astrobiological Perspective: Framing Human Futures in a Planetary Context.” The idea was to show how much of what’s been learned in astrobiology could be brought to bear in understanding what’s happening to us now (a’la climate change, etc.). Going further, we wanted to know how the astrobiological perspective about life and planets might also help us understand what to do next. (Here is a piece I wrote for The New York Times about it, since the paper is behind a pay wall.)

Our robotic probes of Venus and Mars provide one good example of this intersection. Both planets have taught us about climate extremes. Venus is a runaway greenhouse world and Mars is freezing desert. Venus taught us a huge amount about the greenhouse effect. Even better, we have ample evidence that Mars was once a warm, wet and potentially habitable world. That means Mars provides us a laboratory for how planetary climate conditions can change.

So why does that matter so much?

Astrobiology is fundamentally a study of planets and their “habitability” for life. But sustainability is really just a concern over the habitability of one planet (Earth) for a certain kind of species (homo sapiens) with a certain kind of organization (modern civilization). That means our urgent questions about sustainability are a subset of questions about habitability. The key point, here, is the planets in our own solar system, like Mars, show us that habitability is not forever. It will likely be a moving target over time. The same idea is likely true for sustainability — and we are going to need a plan for that.